Distributed Coherent Radar System and Apparatus

Abstract

Disclosed is a distributed coherent radar (DCR) system comprising: first and second radar units and a processer, the radar units each comprising: first and second antennas, aligned in a first direction, and offset in a second, orthogonal, direction, and a linear array of antennas distributed along the first direction and including the first or second antenna; wherein: the second radar unit is configured to receive, at is second antenna, a first signal, being a reflection, from a target, of a first frequency modulated continuous wave (FMCW) signal transmitted by the first radar unit first antenna; the first radar unit is configured to receive, at its second antenna, a second signal, being a reflection, from the target, of a second FMCW signal transmitted by the second radar unit first antenna; and the processor is configured to estimate phase noise from the first signal and the second signal.

1 - 16 . (canceled) 
     
     
         17 . A distributed coherent radar (DCR) system comprising:
 a first radar unit, a second radar unit and a processer, wherein the first radar unit and the second radar unit each comprise:   a first antenna and a second antenna, aligned in a first direction, and offset in a second direction which is orthogonal to the first direction; and   a linear array of antennas distributed along the first direction, wherein a one of the first antenna and the second antenna forms part of the linear array;   
       wherein:
 the second radar unit is configured to receive, at the second radar unit second antenna, a first signal, being a reflection, from a target, of a first frequency modulated continuous wave, FMCW, radar signal transmitted by the first radar unit first antenna; 
 
       the first radar unit is configured to receive, at the first radar unit second antenna, a second signal, being a reflection, from the target, of a second FMCW radar signal transmitted by the second radar unit first antenna; and
 a processor is configured to estimate phase noise from the first signal and the second signal. 
 
     
     
         18 . The DCR system of  claim 17 , wherein the antennas are each elongate along the second direction. 
     
     
         19 . The DCR system of  claim 17 , configured to have an azimuth angle and an elevation angle, wherein the first direction is a tangent to the azimuth angle and the second direction is a tangent to the elevation angle. 
     
     
         20 . The DCR system of  claim 19 , configured to operate over an azimuth angular range of at least 90°. 
     
     
         21 . The DCR system of  claim 19 , wherein the first radar unit and the second radar unit each comprise: a local oscillator. 
     
     
         22 . The DCR system of  claim 17 , wherein the processor is included in one of the first radar unit and the second radar unit. 
     
     
         23 . The DCR system of  claim 17 , wherein
 the linear array of antennas is a sparse array.   
     
     
         24 . The DCR system of  claim 17 , wherein:
 the linear array of antennas is a row of a matrix array of antennas, and   the further antenna is a one of a further row of the matrix array of antennas.   
     
     
         25 . The DCR system of  claim 24 , wherein:
 the matrix array has two rows.   
     
     
         26 . The DCR system of  claim 24 , wherein:
 the further row of the matrix array of antennas is a sparse array.   
     
     
         27 . The DCR system of  claim 25 , wherein:
 the further row of the matrix array of antennas is a sparse array.   
     
     
         28 . The DCR system of  claim 17 , wherein:
 the linear array of antennas is an array of receive antennas.   
     
     
         29 . The DCR system of  claim 17 , wherein:
 the first and second radar units each comprise an integrated circuit configured to pre-process the first and second signals, respectively.   
     
     
         30 . The DCR system of  claim 28 , wherein:
 pre-processing the first and second signals, respectively, comprises down-converting the respective first or second signal by mixing it with the respective FMCW radar signal to produce a down-converted signal.   
     
     
         31 . The DCR system of  claim 29 , wherein:
 pre-processing the respective first or second signal comprises sampling the down-converted signal by an analog-to-digital converter, ADC.   
     
     
         32 . The DCR of  claim 17 , wherein:
 the processor is configured to estimate the phase noise before determining a final range-Doppler map of candidate targets including the target.   
     
     
         33 . A distributed coherent radar (DCR) system comprising:
 a first radar unit, a second radar unit and a processer, wherein the first radar unit and the second radar unit each comprise:   a local oscillator;   a linear array of antennas distributed along a first direction; and   a further antenna aligned with a first antenna of the linear array of antennas along the first direction, and offset therefrom in a second direction which is orthogonal to the first direction, wherein a first transmission path length between the first radar unit first antenna and the second radar unit further antenna, via a target, is equal to a second transmission path length between the second radar unit first antenna and the first radar unit further antenna, via the target.   
     
     
         34 . The DCR system of  claim 33 , wherein the antennas are each elongate along the second direction. 
     
     
         35 . The DCR system of  claim 33 , configured to have an azimuth angle and an elevation angle, wherein the first direction is a tangent to the azimuth angle and the second direction is a tangent to the elevation angle. 
     
     
         36 . The DCR system of  claim 35 , configured to operate over an azimuth angular range of at least 90°.